1. Field of the Invention
One embodiment of the present invention relates to a semiconductor device.
The present invention relates to an object, a method, or a manufacturing method. In addition, the present invention relates to a process, a machine, manufacture, or a composition of matter.
In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. In some cases, a memory device, a display device, a light-emitting device, an electro-optical device, a semiconductor circuit, or an electronic device includes a semiconductor device.
2. Description of the Related Art
A complementary metal oxide semiconductor (CMOS) logic circuit used for a large-scale integrated (LSI) circuit has a problem in that the number of transistors is large. In contrast, in the case of a pass transistor logic circuit, a complicated logic can be formed with a small number of transistors (Patent Document 1). As an example of a pass transistor logic circuit, a cascode voltage switch logic (CVSL) circuit can be given (FIG. 3A). In a pass transistor logic circuit, the number of wirings is small and wiring capacitance is small. Therefore, the capacitance of charge and discharge relating to switching is small, so that power consumption can be low.
A technique by which a transistor is formed using a semiconductor thin film formed over a substrate having an insulating surface has been attracting attention. The transistor is used in a wide range of electronic devices such as an integrated circuit (IC) or a display device. A silicon-based semiconductor is widely known as a semiconductor material that can be applied to the transistor, but an oxide semiconductor (OS) has been attracting attention as an alternative material. For example, a technique for manufacturing a transistor using zinc oxide or an In—Ga—Zn-based oxide semiconductor as an oxide semiconductor is disclosed (see Patent Documents 2 and 3).